Epidemiologic evidence indicates that transmission of HIV by the oral route occurs infrequently, if at all. Laboratory studies by others, and our own preliminary results presented in this proposal, have detected a factor in saliva which inhibits HIV infectivity. The factor(s) appears to be protein, are present in highest concentration in submandibular saliva, and result in a loss of viral infectivity in vitro. In this reaction, two salivary proteins (MW 32,000 and 35,000 daltons) appear to become associated with HIV aggregates. The aims of the present study are to characterize the interaction between the salivary factor and HIV and to purify the protein from normal human submandibular saliva. Antibody or oligomer probes would be generated and used to screen a submandibular gland cDNA library to identify clones expressing the recombinant protein. The purified salivary protein, or the recombinant molecule, would then be used to study the mechanism of interaction with HIV protein(s). Finally, the level of anti-HIV activity in saliva of normal individuals and subjects with xerostomia will be evaluated to determine if decreased salivary flow is associated with a decreased amount of anti-HIV activity. These studies would provide the basis for understanding the role of saliva in modulating HIV transmission. Subsequent studies would investigate the HIV seropositive and AIDS populations to determine if the activity is altered after virus infection.